Fuel burning device



Aug. 4, 1936. J. s. sKELLY FUEL BURNING DEVICE vFiled Feb." 15, 1952 2 Sheets-Sheet 1 Aug. 4, 1936.

J. S. SKELLY FUELBURNING DEVICE 2 sheets-sheet 2 Filed Feb. l5, 1952 INVENTOR Patented Aug. d, i936 ICE eArENr FUEL BURNNG DEVICE poration of Delaware application February 15, rss2, serial No. 592,929

l Claims. (Cl. 11o-47) This invention relates to boilers forming part of heating systems for homes, apartment houses, and the like, and more particularly to stokers therefor.

The cost of fuel with heating boilers, depends largely upon the adaptability of the fuel to control in its rate of delivery to the boiler and in the distribution thereof ovex the re be area and the cost vof the fuel las such.

Certain types of fuel, gas and oil, for example, are much more desirable for heating purposes than solid fuels, as coal or coke, because the burner mechanisms are so ,easily adaptable to There are always available on the market varlf ous grades of coal, and of these grades, slack, as it is generally called, has practically no market value and is, therefore, very inexpensive even though its heating qualities are practically the same as of the better grades of coal.

Therefore, if the proper furnace mechanism were available, such as could be easily regulated and controlled from a remote point, these practically unmarketablevgrades of coal could be used with complete satisfactory results and substan tial savings realized.

An object of this invention is the provision of a stoker for burning coal thatmay be designed for use with heating boilers now in use or as a standard part of such boilers. r

Another object of .this invention is the provision of a Stoker by means of which'coal fuel may be burned efficiently and economically, easily adapted for remote control to obtain uniform heating effects, and capable of burning finely divided coal which ordinarily has practically no market value.

A. further object of this invention is the provision of a Stoker in which coal may be delivered uniformly to and evenly distributedy over the rire bed in order to obtain emcient and economical combustion.

A still further object of the invention is the provision of a simple inexpensive and efcient screw-type underfeed stoker.

In the screw-type of underfeed Stoker, if the screw extends a considerable distance into the retort to obtain uniform coal distribution, heavyr overhanging bearings are required to prevent the screw from rising. and such bearings create friction and increase the power necessary to operate the same.

If the screw extends only a. short distance into the retort it is impossible to secure equal distribution of the coal throughout the full length of the retort and the full burning area thereof.

In either case, the screw feed stoker'does not provide the necessary disturbance or agitation m of the fuel bedto burn coking and caking coals successfully, and for this reason the sliding bottom, pusher and plunger types of stoker are most generally used.

For use in heating boilers, where head room, simplicity of installation and control areA important factors, the screw feed Stoker is most pracl tical.

An object of this invention is therefore to provide a Stoker having' the combined attributes and m advantages oi the screw feed stoker and the sliding bottom, pusher and plunger types of A Stoker,` without their inherent disadvantages.

Other objects ofthe invention will, in part, be

rapparent and will, in part, be obvious to those I cordance with an embodiment of the invention;

Fig. 2 is a view in section taken on line H-H of Figure 1;

Fig. 3 is an enlarged fragmentary view in section ofa detail embodied in the device shown in Fig. l;

Fig. 4 is an end view of a modied form of cam detail adapted for use in the Stoker of Figure i.;

Fig. 5 is a view in side elevation, partly in secnon, of the cam detail shown in rig. 4,;

Fig. 6 is a view in perspective of a pin for supporting cam rollers embodied in the mecha= nisxn shown in Figs. 4 and 5; r

Fig; '7 is ay fragmentary view in section taken on line VIII-VH Iof Fig. 2, showing the construction and arrangement of elements forming the tvryer of the Stoker;

Fig. 8 is a top pian View of a detail forming part of the iuei distributing and agitating means embodied in the Stoker; and 5i? Fig. 9 is a fragmentary. view, similar to Fig. l, showing a modified forni of Stoker embodying the invention. y

Throughout the drawings and the specification, like reference characters indicate' like parts.

The stoker embodying the present invention is adapted for use in heating boilers for homes, apartment houses and the like, and designed to .burn various grades of fuel, efficiently. Such a 5 stoker may, be controlled Iautoiriatically so that the rate of combustion may be effectively regulated to suit the requirements for heat.

The particular stoker illustrated comprises a retort I to which coal is fed by means of a screw 2, and a movable member 3, operating in the retort, having auxiliary distributors or agitators 4 thereon arranged to rake and distribute the coal uniformly over theretort area and to agitate the re bed.

As shown in the drawings,'the retort is disposed` in an air chamber 5 to which air for combustion is supplied under pressure. The retort and air chamber are designed to be disposed in a furnace (not shown) in such position that the fire bed in the retort is near to or slightly below -the water line 'of the heating boiler, in case the heating system is of the hot water, steam or vapor type.

Fuel, such as coal, in a relatively finely dividedv state is fed to the retort, as required, by means of the screw 2 which is disposed in a screw housing 5. The screw may be driven by a motor M, -preferably an electric motor, the operation of which may be controlled from a remote point (by means of a thermostat or equivalent means) where it is desired to maintain the temperature constant at some predetermined value. The motor M drives a fan F which supplies forced draft, or air under pressure to the air chamber 5.

' The retort, as shown in Fig. 2,v is substantially U shape in transverse section, having an open top and closed bottom. 'I'he forward end of the retort is closed by means of an upwardly -inclined wall 1, and the rearward end thereof tervminates in a tubular portion 8 having a flange 9 adapted to register with the flanged end of the feed screw housing 6.

The ret'ort may be cast either as a single integral unit or it may be made up from a plurality 5 of cast sections such as a, b, and c placed end on end as shown in Fig; 1. v

The chamber 5 comprises a bottom plate I0, vertically disposed side plates II and endA plates I2 and I3. The sides of the bottom plate may be oaflanged upwardly, as shown at I l, and the side plates bolted to these flanges as indicated.

In order that the retort may be spaced from the bottom plate of the air chamber, depending lugs I5 are formed on vthe bottom thereof which rest on the bottomplate. To provide for holding the retort in the proper position, the bottom plate is provided with upwardly extending lugs I8 between which the dependingflanges of the retort are disposed.

In order that air for combustion may be di-` rected into and across the top of the retort where combustion takes place, a twyer I1 preferably hollow is provided.

The twyer bridges the space between the side and end walls of the retort and air chamber and is supported thereon. Thus, the twyer, in conjunction with the retort, forms a closure, cover, or roof for the air chamber.

The twyer is preferably made up from a plurality of sectional and removable twyer blocks I8 and I8', the latter being placed at the ends of the retort. As shown, each twyer block has a top wall I9, a side wall 20, a front wall 2|, in which openings l22 are formed and through which air flows to the fuel or iire bed at a point directly above the top of the retort, and an open bottom. The outer ends of the twyer blocks I8 rest on flanges 23 formed at the upper edges of the air chamber side walls II and the outer ends of boxes I8' reston anges 23. In order to hold the twyer blocks in position, the outer ends thereof may be provided with lugs 24 which register in openings or apertures 25 formed in flanges 23. 'I'he inner ends of the twyer blocks may be formed with hook shaped portions 25 which over- 1() hang the sides of the retort.

The twyer blocks, as shown, are open at their bottom side and at one of the vertical sides, but when mounted in position as shown in Fig. '7,v the open side of each twyer block is closed by 15 the side wall 20 of an adjacent twyer block, thereby forming a plurality of parallel disposed passageways 21 which communicate with the air chamber. As shown in Fig. l, the openings 22 in the. front Wall of the twyer blocks are alined 20 and separated from each other by the intervening side walls 28.

The fuel to be fed to the retort I may be stored in a hopper 28 having an open bottom which is disposed over a/housing 29 in which the forward 25 end of the feed screw-2 operates. The feed screw lies in the bottom of the housing and is mounted in a bearing 30 secured in a side wall 3l thereof. 'Ihe opposite side wall of housing 29 has an opening 32 through which the screw projects into 80 the feed screw housing 6. `As shown, the feed screw housing is secured to housing 29 and to end wall I3 of the air chamber 5 so that it will be held in the proper operating position and in alinement throughout its full length.

Since the feed screw is driven at` a relatively low speed, one or two revolutions per minute for example, the screw` is driven from motor M througha speed reducer or gear reduction mechanism 34 of any standard design suitable for the 40 purpose. The power take-off shaft 35 of the speed reducer is coupled to the feed screw as indicated at 36. I In order that air for combustion may be introduced to air chamber 5, the feed screw housing is 45 enclosed in a casing 31 which may be bolted or otherwise secured `to the hopper housing 29, the wall I3 of the air chamber, and the base 38 on which the hopper housing, the motor, and speed reducer mechanism are mounted. The air de- 50 at the entrance to the retort and is confined al- G0 K most wholly within the housing 6. Therefore, the fuel delivered to the retort is pushed forwardkly bythe coal entering behind it from the feed screw. If the retort extends for a substantial distance from the free end of the feed screw, it will 65 be apparent that there will be a tendency'for the fuel to accumulate or pile up at a certain point, resulting in uneven distribution -of the fuel throughout the retort area.

Inv order to secure uniform distribution of 70 the incoming fuel to all parts of the retort, and also to secure agitation of the re bed, the movable member 3 is given a reciprocating motion. The member 3 with its member 4, while reciprocating,i rakes the fuel to` andA fro in the 75 aoaaeee retort causing the same to be uniformly distributed throughout the length of the retort and over its fuel burning area, and prevents piling up of the fuel at different points longitudinally of the retort. Since members t extend upwardly from member 5, the fire bed will be agitated sumciently to prevent caking of the fire bed. Member 3 with its agitating or raking members d thus, in effect, functions as a sliding bottom.

Member 3 may comprise a bar somewhat triangular in transverse section with the apex of the triangle disposed lowermost. The forward end of the bar extends through an opening in the upwardly inclined Wall of the retort which is lined with wear resisting member d2. The rearward end lof the bar extends through an opening in a wall M of the retort at a point immediately above the tubular portion d thereof. In order that the bar may have support at its middle portion, supporting iianges or lugs d5 and i6 are provided, the outer ends of which rest on pads or lugs dl formed integrally with the side walls of the retort.

The distributing and agitating members d, as shown in Fig. 8,. comprise a base 58 having an upwardly extending transverse web or vane .d5 and a stiffening rib '50 that runs lengthwise along the middle of the base.

Since bar 3 runs lengthwise and at the middle of the retort, the'incoming fuel will be divided by the wedge-like bar and caused to move upwardly on each side thereof along the side walls of the retort. As the fuel moves upwardly along the side walls of the retort, the agitating and distributing members d move or rake the fuel back and forth to secure the desired disy ytribution and agitation of the fuel bed.

In order that the agitating and distributing mechanism may be reciprocated when the feed screw is operating, bar 5 is coupled by means of a. connecting rod 5l to a cam 52. The cam, as shown, is mounted on the power take-olf shaft 35 of the speed reducer mechanism so that as the shaft turns, the cam will reciprocate the connecting rod 5l and the agitating and distributing bar t while the feed screw is operating.

The particular form of cam shown may comprise a wheel, disc, or block 53 having a continuous groove 5d formed in the periphery thereof for the reception of a cam follower or roller 55 carried by a pin 55 extending through the end of the connecting rod, as shown in Fig.

' 1. Fig. 3 shows more cle-arly the form'of the groove in the wheel 53, the roller 55 and the pin 56 by which it is attached to the connecting rod.

The groove 53 has straight sides disposed at substantially right angles to the `axis of shaft 35 so that roller 56 may run freely therein without binding. As is apparent by inspection of Fig. 1, groove 53 is contained in a plane which is disposed at an angle to the axis of shaft 55. so that as member 53 turns, rod 5i and bar 3 `will be given reciprocating motion to affect the result desired.

In the operation of a Stoker such as shown in Fig. l, it may be necessary at times to vary or adjust the stroke of the agltating and distributing bar 3 in order to secure proper distribution of the fuel and the most efficient combustion thereof. When such adjustment is desired, a cam mechanism such as shown in Figs. 4 and 5 may be utilized.

The mechanism shown in Figs. 4 and 5 comprises a hub 58 adapted for mounting on the power take-oh shaft 35 of the speed reducer having a wabble plate 59 thereon. The rim of the wabble plate is preferably straight sided so d that cam rollers or followers Bil and 5i, mounted on the connecting rod 5l may roll freely on the rim without binding.

In order that the throw of the connecting rod may be adjusted to thereby regulate the stroke of the agitator bar 5, one or the other, or both, of rollers t@ and 5l may be adjustably mounted on the connecting rod. As shown, only one of the rollers is made adjustable lengthwise of the connecting rod; namely, rollertd. As shown, roller 55 is mounted on a pin 62 which has a square or polyhedral portion 63 adapted to be received in a slot 641 formed on the connecting rod. The upper portion of the slot is partially closed by flanges 55 spaced apart sufficiently to 20 accommodate the screw thread portion of the roller pin. Thus, the pin may be moved longitudinally of the slot either away from or towards the wabble plate and the pin secured in piace, by means of a nut 65.v Thenut, when tightened, 25 clamps the overhanglng flanges 55 between the shoulder on the pin and a washer 6l, thereby securing the roller pin positively in position. A set screw 5B may be utilized to assist ,in making the adjustment and to act as a stop for the 30 roller pin in one direction.

It will be apparent that when both of the rollers 55 and l'contact at all times with the rim of the wabble plate, the stroke of the agitator bar will be equal to the throw of the cam; 35 and that if the rollers are separated a distance greater than the width of the rim, the throw of the agitator bar will be less than the throw of the cam. Therefore, the farther the rollers are separated from each other, the shorter will be 40 the throw of the agitator bar. In practice, the throw of the agitator bar may be so adjusted as to insure the proper distribution of the coal throughout the length of the retort and the proper agitation of the fire bed.

To avoid bridging of coal across the throat of the hopper housing and the consequent interruption in the feed thereof to the retort, the connecting rod 5i may be provided with an agitator arm 59 that extends upwardly towards the 50 bottom of the hopper 28. As the connecting rod reciprocates, arm 55 continually agitates the coal coming from the hopper and prevents the same from bridging, thereby assuring a continuous feed of coal to the feed screw.

The operation of the Stoker mechanism disclosed in Fig. 1 issubstantially as follows: The hopper and the retort having been filled with coal, waste or kindling is thrown on the coal in the retort and ignited. The lburning waste 60 or kindling will set fire to the coal and when combustion is well established the motor may be started. When the motor is set 'in operation the feed screw delivers fresh coal and the fan supplies the air chamber with air under presthe coke residue reachesA the re bed proper. Efli.-

cient combustion of the coal is, therefore, attained. Since the volatile matters are burned as they pass through the fire bed, soft coal may be burned Without causing an objectionable amount of smoke to be emitted.. In fact, by properly adjusting the rate of deiivery of air and fuel, the smoke emitted from the furnace will be practically unnoticeable.

10 As the combustion process continues, the ashes are discharged over the sides of the top of the twyer blocks and collected on the top walls thereof. As these walls slope downwardly, the ash if it piles up, will fall periodically towards the air l5 chamber side walls I I, and may be swept off with a scraper of some sort and removed from the furnace', as required.

While, in Fig. 1, the feed screw is shown as being disposed below the level of the pusher and dis- 20 v-tributor bar 3, it may be desirable to mount the feed screw at a higher level as shown in Fig. 9, for

example. 'I'he feed screw housing 6 of the stoker in Fig. 9 is coupled to the retort I at a higher level than in Fig.- 1, thereby providing room or space below the same for a raking or distributing-bar 'II and a connecting rod 12. The connecting rod, of course, would run under the hopper housing 29 and be coupled to the cam 52 to give the bar the reciprocating motion described in connection with 30"Fig l. ,The bar 1I carries distributing and agitating members 4, such as shown in Figs. 1 and 8.

The agitator and distributor bar 1I, as shown, is disposed longitudinally of the retort with one end extending through the upwardly sloping wall 'l' thereof. A bearing plate 13, secured to the retort wall I has a wear portion 'I4 located within the opening to resist upward thrusts of the bar and to protect the sloping retort wall against the wearing action which would otherwise result be- 40. tween the wall and the bar. 'I'he wear portionl 1I when worn may be removed and replaced.

Since the air chamber in which the retort is disposed, and the twyer, which is made up of individual twyer blocks of the stoker in Fig. 9 are 43 substantially the same in all essential particulars as in the stoker of Figure 1, similar and corresponding parts are designated by the same reference characters.

In the stoker of Fig. 9, coal, in a finely divided state, is fed by the fed screw into the retort on top of the pusher and distributor bar ,II. Since the bar reciprocates when the feed screw is in motion, the coal delivered to the retort is rakedA .back and forth so as to maintain the thickness of o the coal substantially uniform throughout the full length of theretort. The pusher bar with its distributing elements in addition to providing uniform distribution of coal also agitates4 the fuel bed to prevent caking of the coal at the top of the retort, thereby insuring that combustion will take place efficiently and. rapidly. In 'all other respects, the stokers of Figs. 1 and9 operate in sub- 4 stantially the same manner.

65* The stoker motor M may be controlled by means of a thermostat located at some convenient point at which it is desired to maintain the temperature at some predetermined value. thermostatic mechanisms suitable for thisvpur- 70 pose are well known in the art and available on the market, it is believed unnecessary to illustrate such devices herein. A These devices are mentioned merely to show that the stoker herein disclosed is adapted to be started and stopped -ac- 75 'v cordlng to the requirements forI heat so that only Since so much fuel will be burned in the furnace as is required to satisfy the demand for heat.

It will be apparent to those skilled in this particular art that the stokers herein shown admit of various modifications and changes without de- 5 parting from either the scope or the spirit of the invention. It is desired therefore 'that only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a stoker, the combination with a container adapted to contain coal, and a retort in which coal may -be burned adapted for mounting in the combustion chamber of a furnace, of a screw con- 151i with a container adapted to contain coal, and a retort in which coal may be burned adapted for mounting in the combustion space of a furnace,

of. a feed screw housing connecting said retort and container, a screw in said housing having its discharge end terminating at the entrance to the retort, a horizontally reciprocating member disposed in the retort having a raking element ther.e;v on projecting upwardly towards the top of the retort and disposed in the path of movement of the coal delivered by the screw to the retort, said element as it moves back arid forth with the reciprocating member, raking and distributing the coal throughout the retort area, and means for operating the screw and-reciprocating member.

3. An underfeed stoker unit comprising an air chamber. having a retort therein, the retort having an open top, a screw feederv for delivering fuel through an opening in one end of said stoker, and a reciprocating member having vertically disposed vanes thereon adapted to distribute the fuel, delivered by the screw, uniformly through-- out the fuel receiving space of the retort.

4. An underfeed stoker unit comprising an air chamber having a retort therein, the retort hav- 1ing an open top, a screw feeder adapted to deliver fuel through an opening in one end of said *retort, a reciprocating member having vertically disposed vanes thereon adapted to distribute the fuel delivered 'by the 'screw uniformly throughout the fuel receiving space of the retort, and a hollow twyer located at the top of the retort along the border thereof, the interior of said twyer being in communication with said air chamber, there being openings in the twyer through which' air may fiow and be directed across the top of said retort.

5. A stoker adapted for mounting as a unit in operative relation to a furnace comprising a box,

a retort of trough-shape mounted in spaced relation to the bottom, 4side and end walls of the box, the forward end wall of theretrt sloping upwardly atan acute angle from the bottom of the retort, a twyer mounted on the tops of the sideand end walls of the retort and box, thereby forming a closed spaceabout the retort into which air may be directed vunder pressure, the twyerl being provided with openings disposed around the top ofthe retort through which air may discharge in a direction across the top of same, van 4 agitator and distributor bar mounted for reciprocating motion along the bottom and longitudinally ofthe retort, a screw conveyor disposed: to deliver fuel to the retort at a point 75.

of and providing fuel supporting surfaces onv either side thereof, a hopper removed from said retort, a screw for delivering fuel from said hopper to said retort through said fuel receiving opening, agitators located within said retort below the upper" edges thereof and means for rotating said screw and for reciprocating said agitators longitudinally of the retort and in unison with vthe rotation of said screw to effect distribution of the fuel so delivered throughout the length of said retort and over said fuel supporting surfaces.

7. In combination in an underfeed stoker, a retort having a fuel receiving opening at one end thereof and below the upper edges thereof, fuel supporting and air`delivering elements located adjacent said retort and constituting a vertical extension thereof, a fuel hopper removed from said retort, a screw for delivering f uel from said hopper to saidretort through said fuel receiving opening, means for rotating said screw reciprocatory means located withinv said retort and movable back and forth longitudinally thereof' to distribute and breakup the mass of fuel delivered to said retort by said screw, and means for driving said vscrew and reciprocatory means in unison.

8. In combination in a stoker, an open top retort having a fuel delivery opening at one end thereofv below the upper edges thereof, air delivery elements located around said retort and constituting anl extension of the upper edges thereof, a fuel hopperremoved from said retort, a screw for delivering fuel from saidvhopper to said retort through said fuel delivery openingrv agitators located within said retort below the upper edges thereof and below the axis of said screw, and means for rotating said screw and reciprocating said agitators in unison with the rotation of said screw.

9. In combination with a stoker, an open top retort having a fuel'delivery opening at vone end thereof wholly below the upper edges thereof, air delivery and fuel supporting elements located around said retort and constituting a vertical extension thereof, a fuel hopper removed from said retort, a screw for delivering fuel from said hopper to said retort through said fuel delivery opening, fuel distributing mechanism disposed for movement lengthwise of and located within said retort and below the upper edges thereof, means for rotating said screw, and a cam driven by said means for reciprocatingvsaid mechanism within lsaid retort and in unison with the rotation of said screw whereby fuel is delivered to the retort by the screw and distributed throughout the full length thereof by said distributing mechanism.y

10. In an underfeed stoker, the combination of an elongated horizontally positioned retort, said retortbeing substantially U shaped in cross section, a fuel hopper positioned longitudinally of said retort and spaced from one end thereof, a horizontally positioned feed screw connecting said hopper and the adjacent end of s'aid retort, said screw terminating adjacent the end of said retort nearest to said hopper and being positioned Y above the bottom of said retort, the end wall of said retort ,opposite to said screw sloping upwardly from the bottom of sai retort, reciprocable feed means positioned on the bottom of said retort between the end of saidtscrew and said sloping end wall, and means for simultaneously rotating saidfeed screw and reciprocating saidl feed means. l

' JOHN S. SKELLY. 

